1. Field of the Disclosure
The present disclosure relates to an image display device including a barrier cell and a method of fabricating the same, and more particularly, to an image display device including a barrier cell, capable of preventing light leakage due to spacers by adjusting the arrangement of the spacers in the barrier cell, and a method of fabricating the image display device.
2. Discussion of the Related Art
Recently, with the development of information society, demands in the display field are increasing in various forms, and various image display devices capable of implementing 3-dimensional (3D) images as well as 2-dimensional (2D) images have been developed.
Human feels depth and cubic effect of images depending on various psychological and memory factors as well as binocular disparity due to the distance between the eyes.
A 3D image display method that provides cubic effects using the physiological factor of eyes is a stereoscopic type.
The stereoscopic type is based on stereography in which when 2D associated images including disparity information are provided to left and right eyes that are about 65 mm away from each other, the brain combines the 2D associated images to create spatial information before and after a display plane, thereby expressing the cubic effect.
The method of expressing cubic effects can be classified into a glasses-type method in which a user wears special glasses, and an autostereoscopic method using a lens array, such as a parallax barrier or lenticular, on a display plane, according to the location at which the cubic effect is substantially made.
In general, the autostereoscopic method is excellent in view of 3D brightness, compared to the glasses-type method.
A stereoscopic image display device includes a display panel that displays left-eye images and right-eye images, respectively, and a viewing zone generating unit that is disposed above or below the display panel. Lately, studies into the stereoscopic image display device are actively being conducted since it allows users to view 3D images without having to use any additional means.
The viewing zone generating unit may include a lens array, such as a parallex barrier, lenticular, etc.
Particularly, in the case of using a barrier cell, whether a liquid crystal layer functions as a barrier may be determined according to whether a voltage is applied.
An image display device including a barrier cell can select a 2-dimensional (2D) mode and a 3-dimensional (3D) mode.
Hereinafter, an image display device including a barrier cell will be described with reference to drawings.
FIGS. 1 and 2 are views for explaining the arrangement of spacers in a conventional barrier cell 20.
As illustrated in FIG. 1, the conventional barrier cell 20 includes third and fourth substrates 21 and 29 that are spaced apart from each other in a manner to face each other, and a second liquid crystal layer 26 formed between the third and fourth substrates 21 and 29.
A first protection layer 23 is formed on the third substrate 21, and a plurality of first electrodes PXL are formed at intervals on the first protection layer 23. A second protection layer 25 is formed on the first electrodes PXL, and a plurality of second electrodes Vcom are formed at intervals on the second protection layer 25.
Signal lines may be formed between the third substrate 21 and the first protection layer 23.
Each first electrode PXL may be formed in correspondence to the space between two neighboring second electrodes Vcom, and each second electrode Vcom may be formed in correspondence to the space between two neighboring first electrodes PXL.
In other words, the first electrodes PXL and the second electrodes Vcom may be alternately arranged.
A third electrode 27 is formed in the form of a film on the lower surface of the fourth substrate 29, and a second liquid crystal layer 26 is formed between the third and fourth substrate 21 and 29.
Also, black matrices BM may be formed between the fourth substrate 29 and the third electrode 27 to cover signal lines, etc.
The liquid crystal molecules of the second liquid crystal layer 26 may be aligned according to an electric field that is formed by voltages applied to the first electrodes PXL, the second electrodes Vcom, and the third electrode 27, respectively.
First, second, and third driving voltages may be applied to the first electrodes PXL, the second electrodes Vcom, and the third electrode 27, respectively.
The first, second, and third driving voltages that are applied to the barrier cell 20 may be a part of a pixel voltage and a common voltage that are applied to a display panel.
By appropriately adjusting the first, second, and third driving voltages, the barrier cell 20 may function as a parallax barrier that divides incident light of the second liquid crystal layer 26 to emit the divided light beams in different directions.
In the conventional barrier cell 20, ball spacers BS for maintaining cell gaps are randomly arranged as shown in FIG. 1.
As a result, there is a problem in which cell gaps become non-uniform due to step heights made on the deposition surfaces of the third and fourth substrates 21 and 29.
Also, as shown in FIG. 2, since the ball spacers BS are arranged regardless of black areas Br_B and white areas Br_W of the barrier cell 20, light leakage occurs due to the ball spacers BS when a 3D image is displayed.
When a 3D image is displayed, the barrier cell 20 is divided into the black areas Br_B and the white areas Br_W, wherein the black areas Br_B block light emitted from the display panel, and the white areas Br_W transmit light emitted from the display panel.
Accordingly, when a 3D image is displayed, the black areas Br_B need to completely block light. However, in the conventional barrier cell 20, since the ball spacers BS are arranged in areas corresponding to the black areas Br_B, light leakage occurs.
In other words, liquid crystal surrounds the ball spacers BS, and light emitted from the display panel is blocked or transmitted according to the alignment of the liquid crystal. If the anchoring force of an alignment film is weakened due to physical force during a rubbing process, light leakage may occur in black areas Br_B due to changes, etc. of the liquid crystal molecules around the ball spacers BS.